The brake control equipment on most locomotives presently in use on American railroads embody a charging cut-off pilot valve device normally operable responsively to an emergency rate of reduction of pressure in the train brake pipe to cause the supply of fluid under pressure to (1) the brake pipe cutoff valve of the brake valve thereby effecting closing of this cut-off valve to render the relay valve of the brake valve ineffective to supply fluid under pressure to the train brake pipe, (2) the power cut-off switch to cut off the propulsion power of the locomotive, (3) the dynamic brake cut-out switch to cut out the dynamic brakes, and (4) the sanding equipment to cause sanding of the rails. Consequently, the car control valve, if of the usual type which includes both a service portion and an emergency portion that embodies a brake pipe vent valve for venting fluid under pressure from the brake pipe at a fast rate, on each car in the train, and also the control valve on the locomotive, thereupon operates in response to the emergency rate of reduction of pressure occurring in the train brake pipe to effect an emergency brake application on the respective vehicle in the train. However, it has been found that if cars hauled by the locomotive are provided with a control valve that does not have the above-described emergency portion that embodies a brake pipe vent valve, such as is the case with many control valves of foreign manufacture, the rate of reduction of pressure in the train brake pipe, subsequent to a train separation at a location remote from the locomotive, is less than an emergency rate. Therefore, the charging cut-off pilot valve device is inoperative to cause (1) closing of the brake pipe cut-off valve, (2) cut off of propulsion power, (3) dynamic brake cut out and (4) rail sanding.
Accordingly, it is the general purpose of this invention to provide a brake control apparatus for locomotives used to haul cars that are provided with control valves that do not have an emergency portion having a brake pipe vent valve, that embodies means manually controlled by the engineer to provide fast charging of the train brake pipe and thereafter restricted flow of fluid under pressure to the brake pipe, and means automatically operable, while the flow to the train brake pipe is so restricted, in response to a train separation to cause (1) cut off of propulsion power, (2) dynamic brake cut out (3) rail sanding and (4) a service brake application on the locomotive and all the cars in the train, irrespective of the type of control valve provided on the locomotive and cars, unless suppressed by the engineer.